Side-by-side self-crimping conjugate filaments



United States Patent ABSTRACT OF THE DISCLOSURE A side-by-side conjugatefilament is disclosed in which one of the components is a fibre-formingpolyamide or polyester and the other component is a fibre-formingpolyamide/polyester mixture. The mixture is such that one polymer formsa continuous phase with the other polymer dispersed therein in the formof fine fibrils.

13 Claims The present invention is concerned with improvements in orrelating to conjugate filaments and is especially concerned withconjugate filaments in which one component is a polyester of a polyamideand the other component is a polyamide/polyester mixture.

By the term conjugate filament is meant a unitary filament consisting ofat least two polymeric fibre-forming components extending continuouslyalong the length thereof in an adhering sheath/ core or side-by-siderelationship.

It has been proposed in British patent specification No. 805,033 toproduce conjugate filaments in which one component is a polyamide andthe other component a polyester, such filaments having a high potentialcrimp and good crimp retention. However such filaments formed from thesecomponents in a side-by-side arrangement tend to fibrillate, that isseparate into two unitary filaments, during drawing and hence they haveonly limited commercial application. This problem can be alleviated byforming the conjugate filament with the components in a sheath and corearrangement thus effectively preventing fibrillation, however, theproduction of this type of conjugate filament is technically lessattractive than the side-by-side type.

We have now found that a conjugate filament, in which the componentsexist in a side-by-side relationship, having high crimp and good crimppermanence and substantially free from fibrillation can be obtainedusing a polyamide and a polyamide/ polyester mixture as the twocomponents. To obtain maximum adhesion it is preferable thepolyamide/polyester mixture should consist of a matrix of the polyamidehaving the polyester dispersed therein in the form of long fine fibrilsto obtain maximum adhesion between the two components. It has been foundthat the polyester fibrils exert a disproportionately large effect onthe physical characteristics of the mixture in filament form, thus theinitial modulus is increased by an amount which is greater than would beexpected from the percentage of polyester present and the filamentsexhibit a spontaneous crimp when the two polyamide components are thesame. Surprisingly good adhesion between the components is obtained whenthe polyamide is the dispersed phase, it being thought that this may bethe result of the polyamide fibrils diffusing into the wholly polyamidecomponent and thereby forming anchor points which prevent fibrillation.Conjugate filaments of this type normally have a higher crimp than thosein which the polyamide is the continuous phase.

We have also found non-fibrillated conjugate filaments 3,488,251Patented Jan. 6, 1970 are obtained when one component is a polyester andthe other component is a poly/polyamide mixture in which the polyesteris the disperse phase.

The present invention does not include those conjugate filaments inwhich a polyester forms one component and a polyester forms thecontinuous phase of the other component, since the dispersed polyamidefibrils add nothing the ability of the filament to crimp or to theadhesion between the components.

The conjugate filaments of this invention crimp spontaneously when heldin a relaxed condition after drawing. Subsequent heat relaxationtreatments further increase the crimp and, surprisingly, it has beenfound that improved crimp is obtained when the filaments are fatigued,that is repeatedly stretched and relaxed under ambient conditions.

Accordingly therefore from one aspect the present invention provides adrawn molecularly oriented spontaneously conjugate filament containingtwo components one of which components is a fibre-forming polyamide orpolyester and the other of which componets is a fibreformingpolyamide/polyester mixture. Preferably the components exist in aside-by-side relationship.

It is preferred that the percentage of polymer constituting the dispersephase in the mixture be not less than 20% and more preferably not lessthan 25% of the combined weight of the polymers in the mixture.

It is also preferred that in the polyamide/polyester mixture thepolyamide is the continuous phase and the polyester is dispersed thereinin the form of fibrils having a length of not less than microns.

The polyamide/polyester component should preferably have an initialmodulus of at least 50 gm. per denier per of extension, measured at 2%extension when in the form of a unitary filament, and a glass/rubbertransition temperature measured in the dry state of not less than 100 C.

In order to avoid fibrillation it is preferred that the heterofilamentsare drawn immediately after spinning, or are stored at a relativehumidity of at least 65% and a temperature of 7173 F. before drawing ifthere is a time lag between spinning and drawing.

From another aspect therefore the present invention provides a processfor the manufacture of a heterofilament as hereinbefore definedcomprising simultaneously extruding the components through the sameextrusion orifices in a side-by-side relationship, solidifying andwinding up the filament onto a package and storing the package at arelative humidity of at least 65% and a temperature of 71-73 F. beforedrawing or drawing immediately after completion of winding the filamentonto the package, drawing the filament by at least three times itsoriginal length and relaxing to allow the crimp to develop.

Drawing may be carried out by passing the filament between a first andsecond set of rotating rolls, the second set rotating at a greaterperipheral speed than the first, there being, preferably, a snubbing pinpositioned between the sets of rolls to locate the point of draw of thefilament. For best results the filaments should be heated during drawingby passage over a heated plate or by use of a heated snubbing pin, thetemperature of the plate or pin preferably being above 100 C.

Care must be taken in the preparation and spinning ofpolyamide/polyesters polymers to avoid hydrolytic degradation of thepolyester by the action of water on the polyester linkages and to avoidinteraction between the polyamide and polyester components. Suitablepolyester/ polyamide mixture may be prepared and spun as one componentof the heterofilament by the process described in our copending patentapplication No. 46,796/ 65.

The polyamides, when used as one component, may be homopolymers orcopolymers. Suitable polyamides are polyhexamethylene adipamide andpolyepsilon captolactam and copolymers thereof, especially the 80/20polyhexamethylene adipamide/polyepsilon caprolactam copolymer.

tensile tester, extended at a rate of 100 cm./min. to a draw ratio of4.1 and the load released at the same speed: the distance apart of thejaws when the load became zero was used as a means of filament lengthwith the crimp removed (L The test was carried out at normal tem-Polyethylene terephthalate is a suitable polyester to use 5 P atl a t. at v h mid y 0f Th6 c i p as one component. characteristics were as shownin Table 1.

The polyamide/polyester mixture may consist of poly- TABLE 1hexameth'ylene adipamide or polyepsilon caprolactam admixed withpolyethylene terephthalate or the polyester Mlmmum Maxlmum Mean formedfrom ethylene glycol and 4/4' dicarboxy ph n Xy gg g gg'g ethane. Eitherthe polyamide or the polyester may con CF (per stitute the continuousphase, the disperse phase being dis- 5 8' 8 2 8%; tributed therethroughin the form of fine fibrils. For the 6 1111111511: is 1 .9 2.8 purposesof the present invention polyesters include co- ,Meanono teswpolyesters. +Mean of 6 tests.

The following examples illustrate but do not limit the ReversalFrequency (RF) the number of crimp mvenuonreversals per cm. iscalculated from the expression:

Example 1 i RF :r/ a A conjugate filament was obtamed by the extruslonof where r-number of crimp reversals per crimped length apolyhexamethylene adipamide (PHA) and a mlxture of Grim; Permanence (CP)is calculated from the polyhexamethylene adipamide and polyethyleneterephs thalate (PET) (75:25 parts by weight) in a side-by-side pm S1arrangement at a temperature of 285 C. The solidified filament was woundup and stored at a temperature of L a about 72 and a relatlve immidltyof about and where L and a have the same significance as above, andsubsequently drawn at a feedlng speed of 50 ft./m1n. and of crimpedfilament after placing the crimped g ffi f e g g hot g at 2 Wlthoutfilament under a load of 0.3 g./d. for one minute and r1 ation. e amentad a enier o .1 a tenacity then relaxin in th tns-on d stat f0 on t of7.2 g./d. and an extension to break of 18.5%. A fine g 6 un e 1 e e r emmu e. helical crimp having good crimp permanence was ob- Examp tamed fthe j j filament was relaxed at amblent A series of drawn unfibrillatedconjugate filament yarns atmOSPheI'lC Conditions and there was Completeabsence containing ix filaments were prepared in the manner deoffib1'111at10ndescribed in Example 1. Details of the polymer com- Afterrelaxing in water at near boiling point for one ponents, spinning anddrawing temperatures and yarn mlnute and then further relaxing for oneminute out properties are given in Table 2 below.

TABLE 2 Drawing Yam physical properties Conditions Polymer ComponentsSpinning Hotplate Ext. to Example Homotemp., temp., Draw Tenacity break,No. Mixture polymer 0. 0. ratio Denier g./d. percent 2 PET/FHA(75/25)-.- PHA 292 140 5.0 13.7 5.8 14.5 3 PET/FHA (75 25) FHA- 292 204.5 9.8 4.5 36.9 4 PET/PHA (25/75) PET 290 140 5.0 13.3 5.1 16.7

of water the conjugate filament had the following crimp The spunfilaments in the above examples were cooled characteristics: and woundup and drawn immediately or held at a temture of about 72 F. and arelatively humidity of Crlmp ratio (CR): 33% Pm Crimp frequency (CF): 3m about 67% for several hours before drawlng. Under these conditionsseparation of the components was not en- Hellx diameter (d). 2.0 mm. t dd d A fi h 1 h Crimp ratio was calculated from the expression: coun urmgrawmg e lea cnmp avmg good crimp permanence was obtained when the drawnyarn was relaxed at ambient atmospheric conditions. C'.R.= L0 X100 Afterrelaxing in water at near boiling point for one minute and then furtherrelaxing for one minute out of Crimp frequency f the expression water,the filaments had the following characteristics:

CF=n/a (crimps/cm.)

Where CR, percent CF/cm. dmrn. L0=length of uncrimped filament ExampleNo; a=1ength of crimped filament under zero tension 2 28 2 H n=number ofloops in crimped length a of the filament. 58

The spontaneous crimp developed by the filaments obtained in thisexample were characterised in the following experiment. A 10 cm. lengthof undrawn filaments ob- The spontaneous crimp developed by thefilaments of tained above was inserted between the jaws of an instronExamples 2 and 4 was characterised in the manner used in Example 1 at adraw ratio of 4.5, the crimp characteristics are shown in Table 3.

amide/polyester mixture in which the polyester is the continuous phaseand the polyamide is dispersed therein TABLE 3 03*, Denier* percent CF".per cm RF*. per cm. OP+ d. mm.

Ex. N:

{ll/linimum... 10.2 27 2 0.25 0. 33 1.1 2 Maximum 18.0 34 4 0.40 0. 522.3 Mean 15.1 31 a 0. 33 0. 41 1.0 {MinimunLu 9.2 27 4 0. 20 0. 44 0.0 4Maximum. 13.7 30 5 0. 45 0. 80 1.4 Mean 11.4 32 4 0. 31 0. 02 1.2

*Mean of ten tests. +Mean of six tests.

A series of other combinations of polymers was rod in the form of finefibrils. spun as monofilaments at a rate of extrusion of 1.3 g./ min. 9.A filament according to claim 8 wherein the polyand a wind up speed of600 ft./min. The undrawn filaments amide is polyhexamethylene adipamideand the polywere drawn over a heated plate immediately after extruamide/polyester component is polyepsilon caprolactam/ sion and subsequentlyrelaxed in water at near boiling polyethylene terephthalate in which thepolyepsilon capropoint for one minute and then further relaxed for onelactam is the disperse phase and constitutes 25% by weight minute out ofthe water and the crimp characteristics of the mixture.

determined. Details of spinning and drawing and crimp characteristicsare given in Table 4.

10. A filament according to claim 8 wherein the polyamide is polyepsiloncaprolactam and the polyamide/ TABLE 4 Components Spinning Draw Plate 0R C F, Polyarnide Mixture temp. 0. ratio temp, 0. percent per cm. d. mm

6 FHA/PEG (80/20) FHA/PET (20, 80) 288 5 140 74 22 0.8 7 PHA PET/PHA(40/60). 275 4. 5 135 61 3. 5 1. 6 270 4. 5 135 37 2.0 1. 8 275 4. 0 13561 4. 7 1. 6 296 4. 0 150 03 7. l l. 0

*PEC polyepsilon caprolactam. +CPE.2G=polyester prepared from ethyleneglycol and 4,4 dicarboxyplienoxycthane.

There was no evidence of fibrillation during drawing in any of the aboveexperiments.

What we claim is:

1. A drawn molecularly oriented spontaneously crimping conjugatefilament containing at least two components existing in a side-by-siderelationship, one of which components is a fibre-forming polyamide orpolyester and the other of which components is a fibre-formingpolyamide/ polyester mixture.

2. A filament according to claim 1 wherein the poly amide/polyestermixture contains not less than 20% by weight of the disperse phase.

3. A filament according to claim 2 wherein the polyamide/polyestermixture contains not less than by weight of the disperse phase.

4. A filament according to claim 2 wherein one component is a polyamideand the other component is a polyamide/ polyester mixture in which thepolyamide is the continuous phase and the polyester is dispersed thereinin the form of fibrils having a length of not less than 80 microns.

5. A filament according to claim 4 wherein the polyamide/polyestercomponent has an initial modulus of at least 50 g. per denier per 100%extension, measured at 2% extension, and a glass-rubber transitiontemperature of not less than 100 C. when measured in the dry state.

6. A filament according to claim 5 wherein the polyamide ispolyhexamethylene adipamide and the polyamide/ polyester mixture ispolyhexamethylene adipamide/ polyethylene terephthalate.

7. A filament according to claim 2 wherein the polyamide ispolyhexamethylene adipamide and the polyamide/polyester component is amixture of polyhexamethylene adipamide/ and a polyester formed fromethylene glycol and 4,4 carboxy phenoxy ethane in equal proportions byweight.

8. A filament according to claim 2 wherein one component is a polyamideand the other component is a polypolyester component is polyepsiloncaprolactam/polyethylene terephthalate in which the polyepsiloncaprolactam is the disperse phase and constitutes 25 by weight of themixture.

11. A filament according to claim 8 wherein the polyamide ispolyhex'amethylene adipamide and the polyamide/ polyester mixture ispolyhexamethylene adipamide/ polyethylene terephthalate in which thepolyhexamethylene adipamide is the disperse phase and constitutes 25% byweight of the mixture.

12. A filament according to claim 2 wherein one component is a copolymerpolyhexamethylene adipamide and polyepsilon caprolactam containing 20%by weight of the polyepsilon caprolactam and the other component ispolyhexamethylene adipamide/ polyethylene terephthalate containing 20%by weight of polyhexamethylene adipamide.

13. A filament according to claim 2 wherein one component is a polyesternamely polyethylene terephthalate and the polyamide/ polyester componentis polyhexamethylene adipamide/ polyethylene terephthalate containing byweight of the polyamide as the continuous phase and the polyesterdispersed therein in the form of fibrils having a length of not lessthan microns.

References Cited UNITED STATES PATENTS 3,118,011 1/1964 Breen 264--l683,382,305 5/1968 Breen 26417l 3,402,752 9/1968 Beringer.

ROBERT F. BURNETT, Primary Examiner LINDA M. CARLIN, Assistant ExaminerUS. Cl. X.R. 161173; 264-l7l

